The role of environmental light rearing on the rod outer segment membranes of normal and mutant rats possessing the gene for retinal dystrophy will be studied in the vitamin A deficient state and following intense light exposure. The assessment of peroxidation and the role of antioxidants in hydroperoxide metabolism will be studied by enzymatic and physical-chemical procedures in animals up to the age of 60 days. The isolation of pure morphologically intact retinal pigment epithelial cells will permit studies to be extended to these tissues in normal and dystrophic rats.